This invention relates to safety cocks and, more particularly, to safety cocks which are intended to couple a fluid delivery conduit to a chamber. Such safety cocks have particular utility in pipe repair rings were sealant is injected under pressure to a confined chamber defined by the ring to seal off a pipe leak. An example of such a repair ring is shown in U.S. Pat. No. 3,467,141 (the disclosure of which is incorporated herein by reference) and includes an arrangement for sealing off leaks in pipes between abutting flanges which may be applied on site to a leaking pipe without shutting off the flow within the pipe while repairs are being made. The patented invention provides a mechanical sealing means for initially blocking off a circumferential zone where bolted, flanged pipes are abutted and which will permit the introduction of a suitable fluid sealant under pressure within that zone so that any further fluid leakage through the zone defined by each bolt and bolt hole will carry the sealant therethrough to effectively seal the leaking joint. According to the teachings of that patent, semicylindrical sections having a gasketed inner face are applied to the flanges to fence off an area at the flanged joint. The sealant is introduced through fittings which comprise one-way check valves similar to conventional grease fittings. A globe valve is provided to permit excess pressure to be relieved during the sealing operation and that valve is later removed and replaced with a check valve fitting.
While the above-described arrangement is suitable for many sealing applications, there are certain disadvantages in the use of check valve fittings. One such disadvantage is that care must be exercised in maintaining a coupled connection between a high-pressure fluid delivery conduit and the fittings, since the repair man would be subjected to high-pressure sealant and/or fluid pressure from the pipeline if the conduit should become disconnected from its fitting. Furthermore, for many sealing operations, coarse fillers are required in the sealant, such as asbestos shreds, steel wool, or metal particles. Those fillers tend to foul the ball check valve and/or cause the check valve to be wedged open after the conduit is disconnected so that the fitting leaks. Although the leakage of sealant is not particularly hazardous, there exists the possibility of pressurized fluids, such as live steam, leaking through the fitting from the pipeline. A still further disadvantage in the prior art fittings is that those fittings are frequently associated with high temperature pipelines and heat tends to weaken the ball check valve spring, particularly if temperature cycling is involved.
A still further problem with prior art repair ring fittings is that after prolonged use of the repair ring, voids may be formed in the encased sealant by the high pressure fluid from the pipeline. If the sealant is still soft in the vicinity of a fitting adjacent the void, more sealant may be added through that fitting. However, the sealant adjacent and within the fitting is frequently in a solidified state, since that sealant is adjacent cooler repair ring portions, such that with prior art fittings new sealant cannot be readily introduced into the repair ring.